Electromagnet and elevator door coupler

ABSTRACT

An elevator door assembly ( 20 ) includes an electromagnet ( 30 ) use as part of a door coupler for coupling elevator car doors ( 24 ) to elevator hoistway doors ( 26 ). A disclosed example includes an electromagnet core ( 40 ) with a gap ( 50 ) in one of four sides of the core. The gap ( 50 ) directs and concentrates magnetic flux of the electromagnet ( 30 ) to concentrate an attractive force for coupling the electromagnet ( 30 ) with a vane ( 32 ). Disclosed examples includes unique geometric and dimensional relationships to achieve a desired goodness factor.

FIELD OF THE INVENTION

This invention generally relates to electromagnets. More particularly,this invention relates to an electromagnet useful in a door couplerarrangement for elevator systems.

DESCRIPTION OF THE RELATED ART

Elevators typically include a car that moves vertically through ahoistway between different levels of a building. At each level orlanding, a set of hoistway doors are arranged to close off the hoistwaywhen the elevator car is not at that landing. The hoistway doors openwith doors on the car to allow access to or from the elevator car whenit is at the landing. It is necessary to have the hoistway doors coupledappropriately with the car doors to open or close them.

Conventional arrangements include a door interlock that typicallyintegrates several functions into a single device. The interlocks lockthe hoistway doors, sense that the hoistway doors are locked and couplethe hoistway doors to the car doors for opening purposes. While suchintegration of multiple functions provides lower material costs, thereare significant design challenges presented by conventionalarrangements. For example, the locking and sensing functions must beprecise to satisfy codes. The coupling function, on the other hand,requires a significant amount of tolerance to accommodate variations inthe position of the car doors relative to the hoistway doors. Whilethese functions are typically integrated into a single device, theirdesign implications are usually competing with each other.

Conventional door couplers include a vane on the car door and a pair ofrollers on a hoistway door. The vane must be received between therollers so that the hoistway door moves with the car door in twoopposing directions (i.e., opening and closing). Common problemsassociated with such conventional arrangements is that the alignmentbetween the car door vane and the hoistway door rollers must beprecisely controlled. This introduces labor and expense during theinstallation process. Further, any future misalignment results inmaintenance requests or call backs.

It is believed that elevator door system components account forapproximately 50% of elevator maintenance requests and 30% of callbacks.Almost half of the callbacks due to a door system malfunction arerelated to one of the interlock functions.

There is a need in the industry for an improved arrangement thatprovides a reliable coupling between the car doors and hoistway doors,yet avoids the complexities of conventional arrangements and provides amore reliable arrangement that has reduced need for maintenance.

Any new elevator door coupler design must fit within the tight spaceconstraints mandated by codes. For example, an elevator door couplerarrangement must leave a 6.5 mm minimum clearance between the car doorsill and the coupler components on a hoistway door. At the same time a6.5 mm minimum clearance must be maintained between the hoistway doorsill and the coupler components on the car. The total gap between atypical car door sill and a typical hoistway door sill is about 25 mm(one inch). Such space constraints place limitations on the type ofcomponents that can be used as an elevator door coupler. Therefore,strategic arrangement of parts becomes necessary to implement newcoupling techniques.

This invention provides a unique electromagnet design that is suitablefor use in an elevator door coupler that avoids the shortcomings anddrawbacks of previous devices.

SUMMARY OF THE INVENTION

An exemplary disclosed embodiment of an elevator door assembly includesan electromagnet associated with a first elevator door. Theelectromagnet includes a core that has first and second sides aligned atleast partially generally parallel to each other. Third and fourth sidesare aligned at least partially generally parallel to each other and atleast partially generally perpendicular to the first and second sides.The first, second and third sides are uninterrupted while the fourthside includes a gap. A size of the gap is smaller than a spacing betweenthe first and second sides. A vane is associated with a second elevatordoor and positioned near the gap in the fourth side of the electromagnetwhen the first and second elevator doors are appropriately aligned witheach other. A magnetic coupling between the electromagnet and the vanefacilitate the first and second elevator doors moving together. The gapin the core of the electromagnet facilitates directing the attractivemagnetic force of the electromagnet in a manner that enhances a couplingwith the vane.

In one example, the electromagnet is thermally coupled with a doorhanger of the first elevator door such that the door hanger acts as aheat sink for the electromagnet.

The various features and advantages of this invention will becomeapparent to those skilled in the art from the following detaileddescription of the currently preferred embodiment. The drawings thataccompany the detailed description can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates selected portions of an elevator systemincorporating a door assembly designed according to an embodiment ofthis invention.

FIG. 2 schematically illustrates an example electromagnet configurationof an embodiment of this invention.

FIG. 3 shows selected features of the embodiment of FIG. 2.

FIG. 4 shows another example embodiment.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 schematically shows an elevator door assembly 20 that includes aunique door coupler. An elevator car 22 has car doors 24 that aresupported for movement with the car through a hoistway, for example. Thecar doors 24 become aligned with hoistway doors 26 at a landing, forexample, when the car 22 reaches an appropriate vertical position.

The illustrated example includes a door coupler to facilitate moving thecar doors 24 and the hoistway doors 26 in unison when the car 22 isappropriately positioned at a landing. In this example, the door couplerincludes an electromagnet 30 associated with at least one of the cardoors 24. At least one of the hoistway doors 26 has an associated vane32 that cooperates with the electromagnet 30 to keep the doors 26 movingin unison with the doors 24 as desired.

In the illustrated example, the electromagnet 30 is supported on a doorhanger 34 that cooperates with a track 36 in a known manner forsupporting the weight of an associated door and facilitating movement ofthe door. The vane 32 in this example is supported on a hoistway doorhanger 38.

Given the tight dimensional constraints on elevator door couplerarrangements, the illustrated example includes a unique electromagnetdesign that concentrates the attractive, magnetic force for coupling theelectromagnet 30 with the vane 38 so that the elevator doors 24 and 26are appropriately coupled together.

Referring to FIGS. 2 and 3, an example embodiment of an electromagnet 30is shown in a partially cross-sectional, elevational view as seen fromthe top, for example, in FIG. 1. The illustrated electromagnet 30includes a core 40 made from an appropriate ferromagnetic material.Those skilled in the art who have the benefit of this description willbe able to select from appropriate metals, laminations or sinteredpowders for making the core 40 according to the needs of theirparticular situation.

The example core 40 includes a first side 42 and a second side 44 thatare aligned at least partially generally parallel to each other. A thirdside 46 and a fourth side 48 are aligned at least partially generallyparallel to each other. The third side 46 and fourth side 48 are alsogenerally perpendicular to the first side 42 and the second side 44. Inthis example, each side 42, 44, 46 and 48 corresponds to a pole of theelectromagnet.

Each of the first side 42, second side 44 and third side 46 areuninterrupted (e.g., comprises a solid, continuous surface across theside) as can be appreciated from the drawing. The fourth side 48 in thisexample includes a gap 50. In this example, the gap 50 extends along theentire height of the fourth side 48.

Providing a fourth side 48 on the core instead of providing a U-shapefor the core and leaving a gap 50 that is smaller than a spacing betweenthe first side 42 and the second side 44 concentrates the magnetic fluxschematically shown at 52 and the associated magnetic attractive forceof the electromagnet 30 near the gap 50. Only a portion of the magneticflux distribution is schematically shown at 52 in FIG. 2.

By strategically placing the gap 50 relative to the vane 32, thedisclosed example allows for concentrating the attractive magnetic forceused to couple the electromagnet 30 to the vane 32, which facilitatescoupling the elevator doors for movement together.

Although the illustrated example includes generally straight sides and agenerally rectangular configuration, other configurations are possiblethat still include first and second sides arranged at least partiallygenerally parallel to each other, third and fourth sides arranged atleast partially generally parallel to each other and a gap in at leastone of the sides. In other words, a core with a partially circular orirregularly shaped configuration may still have a plurality of sides anda gap that achieves the benefits of the illustrated example. One exampleincludes two sides that are generally arcuate and aligned as mirrorimages of each other such that tangents along corresponding portions ofthe sides are generally parallel. It is not necessary in all exampleuses of an electromagnet designed according to an embodiment of thisinvention to have a generally rectangular core configuration asillustrated.

The illustrated example includes dimensional relationships betweenportions of the electromagnet 30 that have been designed to optimize theattractive force realizable within constraints placed on theelectromagnet by the nature of the elevator door assembly and applicablecodes. As can best be appreciated from FIG. 3, interior surfaces on thefirst side 42 and the second side 44 are spaced apart a distance s,which provides a spacing for receiving at least a portion of a coil 54.Energizing the coil 54 in a known manner results in generating themagnetic field used for coupling the electromagnet 30 to the vane 32,for example. In this example, the gap 50 has a dimension d. The size ofthe dimension d is less than the spacing s. The fourth side 48 in thisexample has a nominal width w on a portion 56 adjacent the gap 50. Thesecond side 44, which is adjacent to the gap 50 in this example, has anominal width w₁ along a portion 66 adjacent to the gap 50. The secondside 44 also has a larger width w₂ along a portion 68 that is furtherfrom the gap 50 compared to the portion 66.

The configuration of the fourth side 48 in this example optimizes theamount of attractive force realizable with the given gap configuration.In this example, the fourth side 48 has a first surface 60 that facesgenerally outward or toward the vane 32. An oppositely facing surface 62faces toward an interior of the core 40. In this example, the surface 62is oriented transverse to the first surface 60. An oblique angle α ofthe orientation of the surface 62 relative to the surface 60 in thisexample depends on other dimensions of the core 40.

In one example, the angle α (shown in FIG. 3) is approximately equal tothe arctangent of the width of the second side 44 divided by the sum ofthe inside space s and the dimension d (e.g., α≈arctan (w₁/(s+d))). Inone example, the nominal width w₁ of the second side 44 is used fordetermining the angle α. In another example, the width w₂ is used (e.g.,α≈arctan (w₂/(s+d))).

In this example, the nominal width w of the fourth side 48 at theportion 56 is selected to have a dimensional relationship to thedimension d of the gap 50. In one example, the nominal width w isselected to be less than or equal to approximately one-half d. As can beappreciated from the illustration, the width of the fourth side 48increases in a generally linear fashion in a direction moving away fromthe gap 50.

The nominal width w₁ of the second side 44 in this example is in a rangebelow 9/10 w₂.

The illustrated example includes a ramped surface 70 along a portion ofthe first side 44 facing the interior of the core 40. In this example,the ramped surface 70 is oriented at an oblique angle relative to thegap 50. The oblique angle α in this example is different than theoblique angle at which the ramped surface 70 is oriented relative to thegap 50. Having angled surface as included in the illustrated exampleincreases the attractive force realizable at the gap 50 compared to anarrangement where the interior surfaces of the core 50 are perpendicularto each other.

As best appreciated in FIG. 2, the illustrated example is thermallycoupled with the door hanger 34 such that the door hanger 34 acts as aheat sink for the electromagnet 30. In this example, the third side 46has an increased thickness compared to the other sides of the core 40.In this example, an aluminum block 72 is used for mounting theelectromagnet 30 to the door hanger 34. The block 72 and the core 40 areheld in place by one or more fasteners 74. The aluminum block 72 allowsa spacing for a portion of the coil 54 to be received between the core40 and the door hanger 34. An appropriate insulation or coating isprovided on the coil 54 to electrically isolate the coil 54 from thedoor hanger 54. The coupling through the aluminum block 72 provides forthermal conduction of heat from the electromagnet 30 through the doorhanger 34. This provides a significant advantage in that distributingthe heat from the electromagnet 30 allows for the example arrangement tofit within temperature limitations placed on such components by elevatorcodes. One example code requires that the temperature not exceed 80° C.The example arrangement allows for meeting this requirement withoutintroducing bulky components that would not fit within the spaceconstraints dictated by other code requirements. The illustration inFIG. 2 shows how one example arrangement fits within the spaceconstraints between an elevator door sill 76 and a hoistway door sill78. The same example complies with heat limitation requirements andprovides sufficient magnetic coupling for reliably moving the doors 24and 26 in unison.

In one example, an electromagnet design like the example embodiment ofFIG. 2 has an attractive force at a 1 mm air gap that is at least twiceas strong and up to almost five times as strong as a U-shaped core thatwould fit within the space constraints. The same example has a goodnessfactor, which depends on a relationship between the attractive force andthe power consumption, that is about five times better than acorrespondingly sized electromagnet having a U-shaped core.

FIG. 4 schematically shows another example arrangement where theelectromagnet core 40′ includes a flange 80 that is useful for mountingthe electromagnet to a door hanger, for example. The example of FIG. 4also includes a flange 82 near the gap 50 on the fourth side 48′.Incorporating the flange 82 allows for more specifically directing themagnetic flux in some examples.

The disclosed examples provides several advantages compared to knownelevator door coupler arrangements. The disclosed examples reducemaintenance and callback frequency. The disclosed examples provide thesame amount of functionality as conventional arrangements with muchfewer parts. Some examples designed according to this invention havelower hardware costs that provide savings up to approximately 30%compared to conventional door couplers. Installation time onsite at thelocation of an elevator system can be significantly reduced because thelocations of the door coupler components can be set in a manufacturingfacility. The clearances or tolerances for arranging the vane 32 and theelectromagnetic 30, for example, are not as stringent as required withmechanical coupler systems. This provides significant cost savings inlabor and installation time.

The disclosed examples fit within the space constraints, providesufficient coupling for reliable door operation and fit within thetemperature restraints on elevator door components.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthe essence of this invention. The scope of legal protection given tothis invention can only be determined by studying the following claims.

We claim:
 1. An electromagnet assembly, comprising: a substantiallyrectangular magnet structure, configured to be operatively connected toa first elevator door, the substantially rectangular magnet structurecomprising a first member, having a length and a width, the length beinggreater than the width, a first end, and a second end distal from thefirst end, a second member, having a length and a width, the lengthbeing greater than the width, a first end, and a second end distal fromthe first end, a third member, having a length and a width, the lengthbeing greater than the width, a first end, and a second end distal fromthe first end, and a fourth member, having a length and a width, thelength being greater than the width, a first end, and a second enddistal from the first end, wherein the second end of the first member isjoined to the first end of the second member, wherein the second end ofthe second member is joined to the first end of the third member,wherein the second end of the third member is joined to the first end ofthe fourth member, wherein the second end of the fourth member isproximate the first end of the first member, wherein the first member issubstantially parallel to the third member, wherein the second member issubstantially parallel to the fourth member, and wherein the second endof the fourth member does not contact the first end of the first member,and a gap is formed between the second end of the fourth member and thefirst end of the first member, the gap having a length that is less thanthe length of the first member, the length of the second member, thelength of the third member, and the length of the fourth member; theelectromagnet assembly further comprising a vane configured to beoperatively connected to a second elevator door, where the vane isfurther configured to be selectively coupled to the substantiallyrectangular magnet structure proximate the gap.
 2. The assembly of claim1, wherein the fourth member has a surface that is at an oblique anglerelative to the gap, and the oblique angle is approximately equal to thearctangent of the width of one of the members that is adjacent thefourth member divided by the sum of the dimension and the spacingbetween the first and second members.
 3. The assembly of claim 1,wherein the fourth member has a first surface and a second surface thatis oriented relative to the first surface at an oblique angle; the firstmember has a first, nominal width along a portion of the first membernear the gap and a second, relatively larger width along another portionof the first member further from the gap; and at least one of the firstwidth or the second width determines the oblique angle.
 4. The assemblyof claim 1, wherein the substantially rectangular magnet structuredefines an outer periphery of the magnet structure.
 5. The assembly ofclaim 1, wherein the gap length is less than one half of the length ofthe first member, the length of the second member, the length of thethird member, and the length of the fourth member, respectively.
 6. Theassembly of claim 1, wherein a magnetic attractive force external to themagnet structure and associated with a magnetic field of theelectromagnet is greatest near the gap.
 7. An elevator door assembly,comprising: an electromagnet associated with a first elevator door, theelectromagnet comprising a core including four three-dimensional sidepieces that collectively establish a generally rectangular peripheryhaving four sides corresponding to the side pieces, a first one of theside pieces and a second one of the side pieces being generally parallelto each other, a third one of the side pieces and a fourth one of theside pieces being generally parallel to each other and generallyperpendicular to the first and second side pieces, the third side piecehaving a length corresponding to a spacing between the first and secondside pieces, the fourth side piece having a length that is less than thespacing between the first and second side pieces such that there is agap between an end of the fourth side piece and the first side piece,the gap having a dimension that is smaller than the spacing between thefirst and second side pieces; and a vane associated with a secondelevator door and positioned near the gap such that a magnetic couplingbetween the electromagnet and the vane facilitate the first and secondelevator doors moving together.
 8. The assembly of claim 7, including adoor hanger associated with the first elevator door and wherein the coreis adjacent the door hanger such that the door hanger absorbs heat fromthe electromagnet.
 9. The assembly of claim 8, wherein at least one ofthe side pieces of the core receives a fastener for securing the core tothe door hanger.
 10. The assembly of claim 9, wherein the at least oneof the side pieces includes an extension that receives the fastener. 11.The assembly of claim 7, wherein the fourth side piece has a surfacethat is at an oblique angle relative to the gap, and the oblique angleis approximately equal to the arctangent of the width of one of the sidepieces that is adjacent the fourth side piece divided by the sum of thedimension and the spacing between the first and second side pieces. 12.The assembly of claim 7, wherein the first side piece has a length thatis generally perpendicular to the length of the fourth side piece; thefourth side piece has a width that is generally perpendicular to thelength of the fourth side piece; the width of the fourth side pieceincreases linearly such that a surface of the fourth side piece facingan interior of the core is at an oblique angle relative to the gap, thefirst side piece has a portion adjacent the gap and the first side pieceincludes a surface along at least some of the length of the first sidepiece facing the interior of the core that is at an oblique anglerelative to the gap.
 13. The assembly of claim 7, wherein the fourthside piece has a first surface and a second surface that is transverseto the first surface.
 14. The assembly of claim 13, wherein the gapextends through the fourth side piece in a direction that is generallyperpendicular to the first surface and transverse to the second surface.15. The assembly of claim 13, wherein the second surface is orientedrelative to the first surface at an oblique angle.
 16. The assembly ofclaim 7, wherein the fourth side piece has a first surface and a secondsurface that is oriented relative to the first surface at an obliqueangle; the first side piece side has a first, nominal width along aportion of the first side piece near the gap and a second, relativelylarger width along another portion of the first side piece further fromthe gap; and at least one of the first width or the second widthdetermines the oblique angle.
 17. The assembly of claim 16, wherein thefirst width is less than about 9/10 of the second width.
 18. Theassembly of claim 16, wherein the portion of the first side piece thatis near the gap is immediately adjacent the gap such that a surface onthe portion of the first side piece establishes one edge of the gap. 19.The assembly of claim 7, wherein the gap has a dimension, the fourthside piece has a nominal width along a portion adjacent the gap, and thenominal width is less than about one-half the dimension.
 20. Theassembly of claim 19, wherein the fourth side piece has another,relatively larger width along a portion further from the gap.
 21. Theassembly of claim 19, wherein the fourth side piece has a width thatincreases from the nominal width along the length of the fourth sidepiece.
 22. The assembly of claim 7, wherein the first side pieceincludes a surface facing the interior of the core that is at an obliqueangle relative to the gap, and the fourth side piece includes a surfacefacing the interior of the core that is at a second, different obliqueangle relative to the gap.
 23. The assembly of claim 7, wherein amagnetic attractive force external to the core and associated with amagnetic field of the electromagnet is greatest near the gap.
 24. Theassembly of claim 7, wherein the length of the fourth side piece isgreater than one-half the spacing between the first and second sidepieces; and the gap dimension is smaller than one-half the spacingbetween the first and second side pieces.
 25. The assembly of claim 7,wherein the generally rectangular periphery defines an outer peripheryof the core.